linux-kernel - Re: [PATCH] evdev: Release eventual input device grabs when getting disconnected

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Date:	Mon, 31 Mar 2008 22:21:10 +0200
From:	Johannes Berg <johannes@...solutions.net>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Björn Steinbrink <B.Steinbrink@....de>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jiri Kosina <jkosina@...e.cz>, Greg KH <greg@...ah.com>
Subject: Re: [PATCH] evdev: Release eventual input device grabs when
	getting disconnected

On Sun, 2008-03-30 at 14:51 -0700, Linus Torvalds wrote:

> On Sun, 30 Mar 2008, Björn Steinbrink wrote:
> >
> > I can't reproduce the bug on my UP box and currently can't afford
> > crashing my SMP box (all the oopses seem to come from SMP kernels, so I
> > guess it needs SMP to crash), so while this doesn't show any new
> > problems, I can't tell whether it actually fixes anything. Testers
> > welcome!

Odd, I can reproduce trivially on UP. The patch definitely helps.

> Ok, I applied this because I will do an -rc8 today or tomorrow, but I 
> really really hope somebody can figure out what made this all start to 
> trigger.

Unfortunately, I can't even bisect, I just tried compiling 2.6.25-rc1
and it failed to link because of __udivi3, __umodi3 and another one (or
similar). A quick look failed to tell me why I get that with -rc1 and
-rc2 but not -rc7.

Below is a simple test program. Run it on any event device, then rmmod
the module the device belongs to and abort the program with ctrl-c.

johannes

#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/input.h>

int main (int argc, char **argv)
{
	int fd;

	if (argc < 2) {
		printf("Usage: grab /dev/input/eventX\n");
		printf("Where X = input device number\n");
		exit(1);
	}

	if ((fd = open(argv[argc - 1], O_RDONLY)) < 0) {
		perror("grab[open]");
		exit(1);
	}

	if (ioctl(fd, EVIOCGRAB, 1)) {
		perror("grab[EVIOCGRAB]");
		exit(1);
	}

	printf("interrupt to exit\n");

	while (1)
		sleep(1000);
}


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